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https://issues.apache.org/jira/browse/CASSANDRA-10728?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15013782#comment-15013782
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Yuki Morishita commented on CASSANDRA-10728:
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In that case, I don't see the need to repair those partition. Both partition
have identical column values associated with.
> Hash used in repair does not include partition key
> --------------------------------------------------
>
> Key: CASSANDRA-10728
> URL: https://issues.apache.org/jira/browse/CASSANDRA-10728
> Project: Cassandra
> Issue Type: Bug
> Reporter: Nadav Har'El
> Priority: Minor
>
> When the repair code builds the Merkle Tree, it appears to be using
> AbstractCompactedRow.update() to calculate a partition's hash. This method's
> documentation states that it calculates a "digest with the data bytes of the
> row (not including row key or row size).". The code itself seems to agree
> with this comment.
> However, I believe that not including the row (actually, partition) key in
> the hash function is a mistake: This means that if two nodes have the same
> data but different key, repair would not notice this discrepancy. Moreover,
> if two different keys have their data switched - or have the same data -
> again this would not be noticed by repair. Actually running across this
> problem in a real repair is not very likely, but I can imagine seeing it
> easily in an hypothetical use case where all partitions have exactly the same
> data and just the partition key matters.
> I am sorry if I'm mistaken and the partition key is actually taken into
> account in the Merkle tree, but I tried to find evidence that it does and
> failed. Glancing over the code, it almost seems that it does use the key:
> Validator.add() calculates rowHash() which includes the digest (without the
> partition key) *and* the key's token. But then, the code calls
> MerkleTree.TreeRange.addHash() on that tuple, and that function conspicuously
> ignores the token, and only uses the digest.
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